Variables

Declaring Variables

Variables must be declared before they are used. Unique names are used to identify variables. To declare a variable, you must specify its type and a unique name. Declaration of variable is not an operator.

Simple types are:

char, short, int, long, uchar, ushort, uint, ulong  integers;

color  integer representing the RGB-color;

datetime  the date and time, an unsigned integer containing the number of seconds since 0 hour January 1, 1970;

Only an integer can be an array index. No more than four-dimensional arrays are allowed. Numbering of array elements starts with 0. The last element of a one-dimensional array has the number which is 1 less than the array size. This means that call for the last element of an array consisting of 50 integers will appear as a[49]. The same concerns multidimensional arrays: A dimension is indexed from 0 to the dimension size-1. The last element of a two-dimensional array from the example will appear as m[6][49].

Static arrays can't be represented as timeseries, i.e., the ArraySetAsSeries() function, which sets access to array elements from the end to beginning, can't be applied to them. If you want to provide access to an array the same as in timeseries, use the dynamic array object.

If there is an attempt to access out of the array range, the executing subsystem will generate a critical error and the program will be stopped.

Access Specifiers

Access specifiers define how the compiler can access variables, members of structures or classes.

The const specifier declares a variable as a constant, and does not allow to change this variable during runtime. A single initialization of a variable is allowed when declaring it.

protected  allows access from methods of this class, as well as from methods of publicly inherited classes. Other access is impossible;

private  allows access to variables and class methods only from methods of the same class.

virtual  applies only to class methods (but not to methods of structures) and tells the compiler that this method should be placed in the table of virtual functions of the class.

Storage Classes

There are three storage classes: static, input and extern. These modifiers of a storage class explicitly indicate to the compiler that corresponding variables are distributed in a pre-allocated area of memory, which is called the global pool. Besides, these modifiers indicate the special processing of variable data. If a variable declared on a local level is not a static one, memory for such a variable is allocated automatically at a program stack. Freeing of memory allocated for a non-static array is also performed automatically when going beyond the visibility area of the block, in which the array is declared.